Protecting electronic circuits from unauthorized access is an important consideration when designing apparatus that use electronic circuits that have or may have sensitive and/or confidential information. For example, point of sale (POS) devices collect confidential information about credit cards or bank account details when a purchase is being made.
The protection of such devices can be achieved by a security device commonly referred to as a security wrap. The security wrap forms a part of the device's security system and identifies an attempt to physically access the protected portion of the device. The security wrap physically covers the electronic components being protected which may be a portion of a PCB, the entire PCB or components like a smart card connector, a secure microprocessor and the like. The security wrap may be flexible so as to be able to conform to the physical shape of the PCB, further reducing the opportunities to access the components.
The security wrap provides an electrical connection between two (or more) terminals forming a part of an alarm circuit of the device. In use, when unauthorized physical entry is attempted by removing the security wrap, the connection is broken and the alarm circuit is activated. The function of the alarm circuit is not a part of the instant invention and depends on the security response of the device being protected which may range from a visual and/or audible indication, to shutting down of the device, disabling the device or in an extreme response to total destruction of the device or the components being protected.
Prior art security wraps may be breached by drilling a hole through the security wrap to access the circuit beneath. The conductor is usually arranged in a pattern, herein referred to a security screen. To be successful, one needs to know the exact location of the point they want to access and the design of the security screen. Commonly this is determined using some form of x-ray inspection, which is expensive or by disassembling a sample product, which is destructive.
If a thief can determine how to hack into one device with a security wrap and determine how to bypass the security screen all similar devices are now compromised as each model uses the same security wrap which is fixed to the same PCB within very tight tolerances to ensure good manufacturability and security. However, these tight tolerances means that the thief, having found out how to access one particular device can now access all devices of the same make and model with a high confidence of success, within a short period of time.